Electric switch



F. E. WARNOCK ELECTRIC SWITCH Aug. 30, 1949;

Filed Dec. 4, 1945 lr'xventcr Frank E. Wan mock,

by 4? h Hi8 Attorney Patented Aug. 30, 1949 ELECTRIC SWITCH Frank E.Warnock, Merwood, Pa., assignor to General Electric Company, acorporation of New York Application December 4, 1945, Serial No. 632,7343 Claims. (01. 200-146) My invention relates to electric circuitdisconnecting switches, and more particularly to those of the load breakswitch type wherein auxiliary arcing contacts are provided to interruptcurrents such as transformer magnetizing currents and the like, inaddition to the main switch members for carrying the normal load currentand disconnecting the circuit.

Such load break disconnecting switches, in a relatively inexpensive yetfully insulated and readily mounted and interconnected form, can be usedwith advantage for both interrupting and disconnecting a high voltagepower circuit at points where conventional power circuit breakers areimpractical or uneconomical. Also it is desirable that electric switchesfor interrupting the magnetizing current of power transformers be of aform adapted to be immersed in a relatively small space in the sameliquid insulating dielectric such as oil or a halogenated hydrocarbon asthe transformer. Thus when arcs are drawn in oil there is always thehazard of fire. On the other hand, when arcs are drawn in anon-inflammable dielectric, there is always the possibility of somedecomposition of the halogenated hydrocarbons and the consequentformation of corrosive decomposition products that are injurious totransformer insulation as well as other parts.

Accordingly it is an object of my invention; to provide a new andimproved form ofload break switch that is capable of efficientlyinterrupting moderate load currents of high voltage power circuitswithin a relatively small hermeticallysealed and evacuated enclosure inaddition to externally carrying the load currents and disconnecting thepower circuits.

It is another object of my invention to provide a switch of the typedescribed above which may be immersed in any form of liquid insulatingdielectric without fire hazard or deleterious effect on the liquiddielectric when operating to interrupt moderate load currents.

Further objects and advantages of my invention will become apparent asthe following description proceeds and the features of novelty whichcharacterize my invention will be pointed out with particularity in theclaims annexed to and forming a part of this specification.

For a better understanding of my invention reference may be had to theaccompanying drawing in which Fig. 1 is an elevational view, partly insection, of an electric switch embodying my invention with the switchshown in the closed position, and Fig. 2 is a view similar to Fig. 1

' electric switch shown in the drawing is illus- McCarty applicationSerial trated as being mounted in air, it should be understood that itis particularly well adapted for being immersed in a liquid insulatingdielectric, in which case it may be mounted in a relatively smallhousing integral with a transformer, as is disclosed for example, incopending Palme and No. 632,735, now Patent No. 2,469,203, May 3, 1949,filed concurrently with the present application, and assigned to thesame assighee as the present application.

Circuit terminals! and 2 are arranged to be electrically interconnectedby a pair of relatively movable. knife switch members illustrated as astationary switchmember or contact 5, electrically connected andsupported from circuit terminal I, and a movable blade or contact 6pivotally mounted as indicated at 'l to circuit terminal 2 and havingload current-carrying overlapping engagement with the switch member 5when the pivotally mounted rotatable blade 6 is in a predeterm nedangular position as shown in Fig. 1. For the purpose of interruptingmoderate load power currents when the electric switch of my invention isto be opened there is provided a relatively small auxiliary circuitinterrupter. generally indicated at 8, which can be carried directly byone of the relatively movable switch members without requiring anyadditional insulating support. As illustrated, circuit interrupter 8 isassociated with stationary contact or 1 switch member 5, and circuitterminal I by means of Z-shaped conducting supporting member 9. Itshould be understood that circuit interrupter 8 might be carried bymovable blade 6 if desired. Circuit interrupter 8 comprises anhermetically sealedenclosure 10 formed or insulating material such asglass, or the like, which is essentially an evacuated envelope forhousing a pair of relatively movable arcing or interrupting contacts IIand I2. Interrupting contact II is illustrated as a stationary contactelectrically connected to stationary current carrying contact 5 by meansof Z-shaped bracket or support 9. Movable arcing contact 12, on theother hand,

is a rod-shaped contact having a portion thereof extending outside ofevacuated envelope l through a flexible member or diaphragm 13. Theportion of rod contact l2 extending outside of housing I0 -is in efiecta contact actuating member and includes at the outer extremity thereofan auxiliary terminal 14 which is positioned outside of housing orenclosure l0. Relatively movable arcing or interrupting contacts II andI2 are preferably biased to the open position by suitable means such asthe flexible diaphragm l3 or if desired, by additional spring means suchas I5.

Supported on movable blade 6 is an auxiliary contact surface in the formof a conducting lever or transfer switch l6. Lever I6 is pivotallymounted as indicated at IT and is normally biased in a counter-clockwisedirection, as viewed in Fig. 1, by resilientmeans, such as a spring l8,such counter-clockwise movement being limited by a stop [9 on blade 6adapted to engage with an extension 20 of lever I6.

The auxiliary contact surface in the form of lever I6, the auxiliaryterminal l4, together with interrupting contacts II' and I2, provide ashunt electrical connection across the relatively movable switch membersand 6. An important feature of my invention is the arrangement of thecurrent carrying contacts and arcing contacts whereby the currentcarrying contacts are first opened thereby shunting all of the powercurrent through circuit interrupter 8. As illustrated in the drawings, aportion of the current is normally shunted through the circuitinterrupter 8 but it will be understood that the circuit throughinterrupting contacts H and I2 may normally be open until just prior todisengagement of the current carrying contacts. Such an arrangement isdisclosed and claimed in the above-mentioned copending application ofPalme and McCarty.

As illustrated by dotted lines in Fig. 2, arcing contacts H and i2remain in current carrying engagement until after current carryingcontacts 5 and 6 have been disengaged and all of the current has beentransferred to the shunt circuit comprising interrupting or arcingcontacts II and I2. Furthermore, contacts 5 and 6 must have separated asuflicient distance before contacts Ill and H separate so that arcingwill not occur at contacts 5 and 6. Spring l8, which is a strongerspring than spring 15, maintains arcing contacts I I and l 2 in a closedposition during the opening movement of blade 6 and until extension oflever [B engages stop l9. Thereafter, arcing contacts II and I2 areseparated under the influence of spring l5 and in view of the highvacuum'in envelope ill the interrupting operation even with very highvoltages is readily accomplished. It will be observed that the auxiliarycontact surface in the form of lever I6 is separated from auxiliaryterminal [4 thereby providing an additional insulating gap in the shuntcircuit including interrupting contacts II and I2. The other gap isprovided by contacts II and [2 which, during the opening operation ofthe switch, are opened and remain open.

During the circuit closing operation the circuit is first completedthrough the shunt circuit includin arcing contacts H and I2 after whichthe main current carrying contacts 5 and 6 are closed to complete thecircuit.

It will be understood that the insulating evacuated envelope It preventsany are which is drawn from, in any way, deleteriously affecting thesurrounding medium whether it be air or oil or other liquid insulatingdielectric.

It should be understood that my invention is not limited to the specificdetails of construction and arrangement thereof herein illustrated andthat changes and modifications may occur to one skilled in the artwithout departing from the spirit of my invention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. In a load break disconnecting switch, a first insulating support fora first circuit terminal, a second insulating support for a secondcircuit terminal, a pair of relatively movable cooperating switchmembers which when brought into face carried by said blade, meansincluding said auxiliary contact surface, said auxiliary terminal andsaid interrupting contacts for providing a shunt electrical connectionbetween said switch members before the members are moved out ofelectrical engagement, a spring mounted on said blade to maintain saidshunt connection during a portion of the opening movement of said switchmembers, a stop for limiting the effective operation of said spring,sprin means for separating said interrupting contacts to draw an arc andextinguish the same within said envelope upon continued opening movementof said switch members and to provide a gap in said shunt circuit, andmeans including said stop for subsequently providing an additionalinsulating gap in said shunt circuit between said auxiliary terminal andsaid auxiliary contact surface.

2. In a load break disconnecting switch, a pair of switch membersintegrally mounted for load current carrying, overlapping engagement andincluding a pivotally mounted rotatable blade, a relatively smallcurrent interrupter having a hermetically sealed and evacuated enclosurefixedly mounted on one of the switch members and provided with a firstinterrupting contact fixedly extendin through the enclosure andelectrically connected to the one switch member, and a secondinterrupting contact extending through and having a flexible seal withthe enclosure through the movement of which the second interruptingcontact engages or disengages the first interrupting contact, anauxiliary movable terminal external to the enclosure mechanicallyconnected to operate the second interrupting contact and electricallyconnected therewith, an auxiliary contact surface carried by andelectrically connected to the other switch member for engaging theexternal terminal to interconnect the interrupter contacts in shunt withthe pair of switch members during current-carrying engagement thereof,resilient biasing means for maintaining engagement between the auxiliarycontact surface and the auxiliary terminal upon disengagement of theswitch members, and means including the auxiliary terminal and theauxiliary contact sur- 5 face for disengaging the interrupting contactsdraw an arc and extinguish the same within the enclosure upon furtheropening of the switch members.

3. In a load break disconnecting switch, a pair of knife switch membershaving load current carrying overlapping engagement and each having aspaced apart insulating support, a relatively small current interrupterhaving an evacuated envelope supported on one of the switch memberssubstantially in the space between the insulating supports when theswitch members are in engagement and provided with a first interruptingcontact extending through the envelope and electrically connected to theone switch member, and a second interrupting contact extending throughand having a flexible seal with the envelope through the movement ofwhich the movable interrupting contact engages or disengages the firstinterruptin contact, an auxiliary movable terminal external to theenvelope mechanically connected to operate the second interruptingcontact and electrically connected therewith, an auxiliary contactsurface extending from and electrically connected to the other of saidswitch members for engaging said movable auxiliary terminal tointerconnect the interrupter contacts in shunt with the switch membersduring current-carrying engagement thereof, resilient means formaintaining engagement between the auxiliary contact surface and theauxiliary terminal to maintain the 6 shunt electrical circuit includingthe interrupting contacts between the current-carrying switch membersafter the disengagement thereof, means including the auxiliary terminaland the auxiliary contact surface for separatin the interruptingcontacts to draw an arc in the shunt circuit and extinguish the samewithin the envelope after the disengagement of the switch members, andmeans including the auxiliary terminal and the auxiliary contact surfacefor providing an insulating gap in the shunt circuit upon continuedopening of the switch members after the disengagement of theinterrupting contacts.

FRANK E. WARNOCK.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 532,594 Scott et al Jan. 15, 1895589,582 Smith et a1 Sept. 7, 1897 594,656 Schwedtmann Nov. 30, 18971,783,279 Burnham Dec. 2, 1930 1,963,418 Pittman et al June 19, 19342,121,180 Vatter June 21, 1938 FOREIGN PATENTS Number Country Date400,716 Great Britain Nov. 2, 1933

